Air conditioning system



oct. z5, 193s. M, P .MAY 2,134,338

AIR CONDITIONING SYSTEM Filed April 17, 1957 -Patented Oct. 25, 1938 UNITED sTATEs 'PATENTol-lflclal 2,134,333 AIR CONDITIONING svs'rEM Maxweu F. May, rales Park, Ill.

Application April 1'1, 1937, serial No. 131,635

5 Claims.

'I'his invention relates to heating apparatus,` and more particularly to such apparatus wherein air is heated by a vheat transfer device having hot ture of this invention is th'at it provides an almost constant gentle current of tempered air; yet another feature of this invention is that it provides, when temperature conditionsrequire it, a strong current of heated air; a further feature of this invention is that the speed of the air passing the heat transfer device and the rate of hot water flow therethrough are increased simultaneously upon an urgent demand for heat; other features and advantages of this invention will become apparent from the following specification and the drawing, in which:

Figure 1 is a side elevation, partly in section, of a hot air plant embodying my invention; Figure 2 1 is a wiring diagram of the power and control cir cuits; and Figure 3 is a modiilcatlon of a portion of the circuit. l

When heating a room, for example, with hot air rather than with radiant heat, it is necessary to prevent stratification vof the air in order to insure personal comfort of th'e occupants of the room. That is, lit is desirable, where outdoor temperatures are below 50 or 55 F., to keep a substantially continuous gentle current of tempered air flowing into the room and circulating therein to prevent stratification. The amount of heat energy thus being continuously delivered to the room must be held relatively low, so that the air temperature and air moticn will not be noticed by the occupants. Since this heat input is not sufficient to equal losses from the house where outdoor temperatures are low it is necessary to occasionally step up the amount of heat input to the room in order to restore the temperature thereof to the desired value. This may be done by increasing both the temperature level and the rate of movement of `the air being supplied through the ducts.

The present invention accomplishes these desired results by employing a heat transfer device or radiator in a portion of the duct, the device being adapted to have a flow of hot water therethrough supplied from any convenient source. The system is so arranged that there is suilicient gravity flow of hot water to temper the air during low `speed movements thereof. When the fan or blower speed is stepped upto supply 'a largeramount of air to the room, upon an urgenty demand for heat therefrom, operation oi' 'a circu-l lating pump is effected tol create an increased positive flow of hot water through the heat transfer device. v

In the particular embodiment of this inven- 5 tion illustrated herewith the heating system is shown installed in a building having an outer wall IIJ, abasement floor II, and a room floor I2. A duct I3 located in the basement and having anexpanded portion I4, housing apparatus to be l hereafter described, draws recirculated air through a return duct I and delivers it through a branch duct I5 and oor grate I6 to the room being heated. It is to be understood that this particular duct arrangement is of no importance, l5 since wall rather than liloor ducts could be used for the delivery of the air,l fresh air could be drawn in rather than using recirculated air, and i the like.

The expanded portion I4 houses a centrifugal 20 blower II for causing a current of air to passv through the-duct to the room, the blower being driven by a variable speed prime mover, here shown as a two-speed electric motor I8. Heat transfer means I9 is provided, the device being of radiator type construction adaptedto achieve efficient transfer of heat units in hot waterflowing therethrough to air passing through in a direction transverse to the water flow. The expanded portion is also shown as here housing a lter 2U for the incoming air. It will be understood that in actual installations `.further airA conditioning devices would be employed, such as air washers, humidiers, or the like. These form no part of the present invention,and are therefore not illustrated.- y

A boiler 2| serves as a source of hot water for the heat transfer device I9, the water flow being up through the pipe 22, across through the pipe 23, thence through the heat transfer device I9, then through pipe 24 from whence two parallel flow courses are provided to the cold water return pipe 25. One of theseflowv paths is through the pump 26 driven by the electric motor 21, which pump provides a. positive forced circulation at a considerable flow rate. The other path is through the by-pass pipe 28 adapted to facilitate gravity ilow when the pump is not in operation and is of such a type as to hinder such flow. 'I'heby-pass pipe is provided with a check valve 29 which will permit free flow from the pipe 24 to the pipe 25, but prevent reverse flow in order* that the pump may not be short-circuited during operation thereof. An kexpansion tank 30 of con- 55 at an approximate temperature of 170 F. An automatic fuel supply means 33 is provided, operatively connected to an aquastat 34 to effect operation of the fuel feeding mechanism whenever the temperature of the water in the boiler 2| drops to 160 or below. A second aquastat 35 is provided in the water supply line to the heat t transfer device I9 to act as a safety device in the event of any failure of the furnace and associated devices. That is, the aquastat 35 controls a ciricuit breaker which opens whenever the temperature of the water in the line drops too low, as, for example, below 140 F., so that'the cool air will not be blown into the room in the event of furnace failure.

Referring more particularly to the diagram of Figure 2, a pair of power lines 36 and 3l from any commercial source supply the current, through appropriate relays, to drive the motors I8 and 2l. A transformer 38 serves to step down the voltage to furnish a supply source for the control circuit effecting the desired operation of the motors.

A temperature responsive demand means 39 preferably located on a wall of the room being heated, is here shown as comprising two mechanically interlocked but electrically independentthermostats or temperature responsive means 40 and 4I. 'I'hese two thermostats are of the circuit closing type, and are preferably so set as to be responsive to slightly different temperatures.

Thermostat 40, for example, may be set to close at 72 F., and thermostat 4I at 71 F. As soon as the temperature of the room drops to 72 (assuming the circuit through the aquastat to be closed, as it normally is), the closing of the thermostat 40 is effectively a demand for heat, since it energizes the coil of the single pole single throw relay 42, which closes the circuit from the power line 36 through the movable, member 43 of the relay 44 to the low speed lead 45 of the motor I8, the power circuit being completed from the motor I8 through the lead 45 to the grounded power wire 3l. 'I'he relay 44 is of the single pole double throw type so arranged that when the coil is not energized the movablemember is in contact with the low speed line 45. This results in operation of the motor I8, and thus of the centrifugal blower II, to force a gentle current of air through the duct to the room. Since gravity circulation causes a continuous low speed ow of water through the heat transfer means I9, this gentle current of air is tempered to a gradient 20 or 25 degrees higher than room temperature.

Should heat loss from the room be such that the gentle tempered current is not sufficient to overcome the loss (it would always be the case where outdoor temperature was much below 50 or 55 F.) the temperature in the room continues to slowly drop until it reaches 71, whereupon the thermostat 4I closes and energizes the relay 4l. This relay closes a power circuit energizing the pump motor 2l and at the same time causes the relay 44 to swing the movable member 49 into contact with the high speed lead 49 of the blower motor I9. Thus the more urgent demand for heat which effected closing of the second thermostat results in increasing the ilow through the heat transfer means, through the positive forced feed of the pump 26,' and simultaneously raises the blower speed to force a strong current of air through the ducts. This strong current of heated air is so arranged as to more than overcome any heat losses from vthe room, and after a brief interval the room temperature would again rise above 71 and thermostat 4I would open, whereupon the pump would cease operation and the blower would return to low speed.

Where it is desired to dispense with the substantially continuous gentle current of tempered air, as at night or when all of the occupants are `away from the house, the switch 49 may be closed to keep the relay 4l continuously energized. Thus, whenever the thermostat 40 closes, as a result of a demand for heat resulting from a drop of room temperature, the fan will at once start at high speed, accompanied by forced hot water feed effected by the pump 26. As soon as the room temperature rises above 72 the thermostat will open and the entire system will again become inoperative. An alternative night switching device is shown in Figure 3, where a double pole single throw switch 50 places the two thermostat circuits in parallel. Again closing of the thermostat 40 will close both circuits and effect high speed operation of the blower, accompanied by forced water feed. This circuit is somewhat preferable to the night switch shown in Figure 2, since in that circuit the relay coil 4l is continuously energized, regardless of the room temperature.

While I have shown and described certain embodiments of my invention, it is to be understood `that it is capable of many modifications.

room; heat transfer means in said duct; means.

for tempering said air, said means including a gravity flow of hot .water through said heat transfer means; temperature responsive demand means in said room; a second temperature .responsive demand means in said room; a fan adapted to force said air through said duct, said fan having at least two speeds; means for rendering said fan operative at a low speed upon a demand from said rst mentioned temperature responsive means, whereby a gentle current of tempered air is forced through said duct to said room; a pump for increasing the flow of hot water through said heat transfer means; and means for rendering said pump operative and for increasing the speed of said fan upon a demand from said second mentioned temperature responsive means, whereby a Astrong current of heated air is forced through said duct to said room.

2. Apparatus of the character claimed in claim 4. Apparatus of the character described, including: an air duct adapted to supply air to a room; heat transfer means in said duct; means for tempering said air, said means including Ya gravity ow of hot Water through said heat transfer means; temperature responsive demand means in said room; means for forcing a gentle current of air through said duct upon a demand from said temperature responsive means; a pump for increasing the flow of hot Water; means for rendering said pump operative and for forcing a strong current of air through said duct upon a more urgent demand from said temperature responsive means; and by-pass means around said pump to facilitate said gravity flow, said by-pass means including valve means preventing short circuiting of said pump during operation thereof.

5. Apparatus of the character described, including: an air duct adapted to supply air to a room; heat transfer means in said duct; means v for tempering said air,`said means including a gravity ow of hot water through said heat transfer means; temperature responsive demand means in-said room; a second temperature responsive demand means in said room; a fan adapted to force said air through said duct, said fan having at least two speeds; vmeans for rendering said fan operative at a 10W speed upon a demand from said first mentioned temperature y responsive means, whereby a gentle current of tempered air is forced through said duct to said room; means for increasing the flow of hot vwater through said heat transfer means; and means for rendering said flow increasing means operative and for increasing the speed of said fanupon a demand from said second-mentioned temperature responsive means, whereby a strong current of heated air is forced through said duct to said room. 

